/**
 * @file
 * Multicast listener discovery
 *
 * @defgroup mld6 MLD6
 * @ingroup ip6
 * Multicast listener discovery for IPv6. Aims to be compliant with RFC 2710.
 * No support for MLDv2.\n
 * To be called from TCPIP thread
 */

/*
 * Copyright (c) 2010 Inico Technologies Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Ivan Delamer <delamer@inicotech.com>
 *
 *
 * Please coordinate changes and requests with Ivan Delamer
 * <delamer@inicotech.com>
 */

/* Based on igmp.c implementation of igmp v2 protocol */

#include "lwip/opt.h"

#if LWIP_IPV6 && LWIP_IPV6_MLD  /* don't build if not configured for use in lwipopts.h */

#include "lwip/mld6.h"
#include "lwip/prot/mld6.h"
#include "lwip/icmp6.h"
#include "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/ip.h"
#include "lwip/inet_chksum.h"
#include "lwip/pbuf.h"
#include "lwip/netif.h"
#include "lwip/memp.h"
#include "lwip/stats.h"

#include <string.h>


/*
 * MLD constants
 */
#define MLD6_HL                           1
#define MLD6_JOIN_DELAYING_MEMBER_TMR_MS  (500)

#define MLD6_GROUP_NON_MEMBER             0
#define MLD6_GROUP_DELAYING_MEMBER        1
#define MLD6_GROUP_IDLE_MEMBER            2

/* Forward declarations. */
static struct mld_group* mld6_new_group(struct netif* ifp, const ip6_addr_t* addr);
static err_t mld6_remove_group(struct netif* netif, struct mld_group* group);
static void mld6_delayed_report(struct mld_group* group, u16_t maxresp);
static void mld6_send(struct netif* netif, struct mld_group* group, u8_t type);


/**
 * Stop MLD processing on interface
 *
 * @param netif network interface on which stop MLD processing
 */
err_t
mld6_stop(struct netif* netif)
{
	struct mld_group* group = netif_mld6_data(netif);

	netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, NULL);

	while(group != NULL) {
		struct mld_group* next = group->next; /* avoid use-after-free below */

		/* disable the group at the MAC level */
		if(netif->mld_mac_filter != NULL) {
			netif->mld_mac_filter(netif, &(group->group_address), NETIF_DEL_MAC_FILTER);
		}

		/* free group */
		memp_free(MEMP_MLD6_GROUP, group);

		/* move to "next" */
		group = next;
	}

	return ERR_OK;
}

/**
 * Report MLD memberships for this interface
 *
 * @param netif network interface on which report MLD memberships
 */
void
mld6_report_groups(struct netif* netif)
{
	struct mld_group* group = netif_mld6_data(netif);

	while(group != NULL) {
		mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
		group = group->next;
	}
}

/**
 * Search for a group that is joined on a netif
 *
 * @param ifp the network interface for which to look
 * @param addr the group ipv6 address to search for
 * @return a struct mld_group* if the group has been found,
 *         NULL if the group wasn't found.
 */
struct mld_group*
mld6_lookfor_group(struct netif* ifp, const ip6_addr_t* addr)
{
	struct mld_group* group = netif_mld6_data(ifp);

	while(group != NULL) {
		if(ip6_addr_cmp(&(group->group_address), addr)) {
			return group;
		}

		group = group->next;
	}

	return NULL;
}


/**
 * create a new group
 *
 * @param ifp the network interface for which to create
 * @param addr the new group ipv6
 * @return a struct mld_group*,
 *         NULL on memory error.
 */
static struct mld_group*
mld6_new_group(struct netif* ifp, const ip6_addr_t* addr)
{
	struct mld_group* group;

	group = (struct mld_group*)memp_malloc(MEMP_MLD6_GROUP);

	if(group != NULL) {
		ip6_addr_set(&(group->group_address), addr);
		group->timer              = 0; /* Not running */
		group->group_state        = MLD6_GROUP_IDLE_MEMBER;
		group->last_reporter_flag = 0;
		group->use                = 0;
		group->next               = netif_mld6_data(ifp);

		netif_set_client_data(ifp, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group);
	}

	return group;
}

/**
 * Remove a group from the mld_group_list, but do not free it yet
 *
 * @param group the group to remove
 * @return ERR_OK if group was removed from the list, an err_t otherwise
 */
static err_t
mld6_remove_group(struct netif* netif, struct mld_group* group)
{
	err_t err = ERR_OK;

	/* Is it the first group? */
	if(netif_mld6_data(netif) == group) {
		netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_MLD6, group->next);
	} else {
		/* look for group further down the list */
		struct mld_group* tmpGroup;

		for(tmpGroup = netif_mld6_data(netif); tmpGroup != NULL; tmpGroup = tmpGroup->next) {
			if(tmpGroup->next == group) {
				tmpGroup->next = group->next;
				break;
			}
		}

		/* Group not find group */
		if(tmpGroup == NULL) {
			err = ERR_ARG;
		}
	}

	return err;
}


/**
 * Process an input MLD message. Called by icmp6_input.
 *
 * @param p the mld packet, p->payload pointing to the icmpv6 header
 * @param inp the netif on which this packet was received
 */
void
mld6_input(struct pbuf* p, struct netif* inp)
{
	struct mld_header* mld_hdr;
	struct mld_group* group;

	MLD6_STATS_INC(mld6.recv);

	/* Check that mld header fits in packet. */
	if(p->len < sizeof(struct mld_header)) {
		/* @todo debug message */
		pbuf_free(p);
		MLD6_STATS_INC(mld6.lenerr);
		MLD6_STATS_INC(mld6.drop);
		return;
	}

	mld_hdr = (struct mld_header*)p->payload;

	switch(mld_hdr->type) {
		case ICMP6_TYPE_MLQ: /* Multicast listener query. */

			/* Is it a general query? */
			if(ip6_addr_isallnodes_linklocal(ip6_current_dest_addr()) &&
			        ip6_addr_isany(&(mld_hdr->multicast_address))) {
				MLD6_STATS_INC(mld6.rx_general);
				/* Report all groups, except all nodes group, and if-local groups. */
				group = netif_mld6_data(inp);

				while(group != NULL) {
					if((!(ip6_addr_ismulticast_iflocal(&(group->group_address)))) &&
					        (!(ip6_addr_isallnodes_linklocal(&(group->group_address))))) {
						mld6_delayed_report(group, mld_hdr->max_resp_delay);
					}

					group = group->next;
				}
			} else {
				/* Have we joined this group?
				 * We use IP6 destination address to have a memory aligned copy.
				 * mld_hdr->multicast_address should be the same. */
				MLD6_STATS_INC(mld6.rx_group);
				group = mld6_lookfor_group(inp, ip6_current_dest_addr());

				if(group != NULL) {
					/* Schedule a report. */
					mld6_delayed_report(group, mld_hdr->max_resp_delay);
				}
			}

			break; /* ICMP6_TYPE_MLQ */

		case ICMP6_TYPE_MLR: /* Multicast listener report. */
			/* Have we joined this group?
			 * We use IP6 destination address to have a memory aligned copy.
			 * mld_hdr->multicast_address should be the same. */
			MLD6_STATS_INC(mld6.rx_report);
			group = mld6_lookfor_group(inp, ip6_current_dest_addr());

			if(group != NULL) {
				/* If we are waiting to report, cancel it. */
				if(group->group_state == MLD6_GROUP_DELAYING_MEMBER) {
					group->timer = 0; /* stopped */
					group->group_state = MLD6_GROUP_IDLE_MEMBER;
					group->last_reporter_flag = 0;
				}
			}

			break; /* ICMP6_TYPE_MLR */

		case ICMP6_TYPE_MLD: /* Multicast listener done. */
			/* Do nothing, router will query us. */
			break; /* ICMP6_TYPE_MLD */

		default:
			MLD6_STATS_INC(mld6.proterr);
			MLD6_STATS_INC(mld6.drop);
			break;
	}

	pbuf_free(p);
}

/**
 * @ingroup mld6
 * Join a group on a network interface.
 *
 * @param srcaddr ipv6 address of the network interface which should
 *                join a new group. If IP6_ADDR_ANY, join on all netifs
 * @param groupaddr the ipv6 address of the group to join
 * @return ERR_OK if group was joined on the netif(s), an err_t otherwise
 */
err_t
mld6_joingroup(const ip6_addr_t* srcaddr, const ip6_addr_t* groupaddr)
{
	err_t         err = ERR_VAL; /* no matching interface */
	struct netif* netif;

	/* loop through netif's */
	netif = netif_list;

	while(netif != NULL) {
		/* Should we join this interface ? */
		if(ip6_addr_isany(srcaddr) ||
		        netif_get_ip6_addr_match(netif, srcaddr) >= 0) {
			err = mld6_joingroup_netif(netif, groupaddr);

			if(err != ERR_OK) {
				return err;
			}
		}

		/* proceed to next network interface */
		netif = netif->next;
	}

	return err;
}

/**
 * @ingroup mld6
 * Join a group on a network interface.
 *
 * @param netif the network interface which should join a new group.
 * @param groupaddr the ipv6 address of the group to join
 * @return ERR_OK if group was joined on the netif, an err_t otherwise
 */
err_t
mld6_joingroup_netif(struct netif* netif, const ip6_addr_t* groupaddr)
{
	struct mld_group* group;

	/* find group or create a new one if not found */
	group = mld6_lookfor_group(netif, groupaddr);

	if(group == NULL) {
		/* Joining a new group. Create a new group entry. */
		group = mld6_new_group(netif, groupaddr);

		if(group == NULL) {
			return ERR_MEM;
		}

		/* Activate this address on the MAC layer. */
		if(netif->mld_mac_filter != NULL) {
			netif->mld_mac_filter(netif, groupaddr, NETIF_ADD_MAC_FILTER);
		}

		/* Report our membership. */
		MLD6_STATS_INC(mld6.tx_report);
		mld6_send(netif, group, ICMP6_TYPE_MLR);
		mld6_delayed_report(group, MLD6_JOIN_DELAYING_MEMBER_TMR_MS);
	}

	/* Increment group use */
	group->use++;
	return ERR_OK;
}

/**
 * @ingroup mld6
 * Leave a group on a network interface.
 *
 * @param srcaddr ipv6 address of the network interface which should
 *                leave the group. If IP6_ISANY, leave on all netifs
 * @param groupaddr the ipv6 address of the group to leave
 * @return ERR_OK if group was left on the netif(s), an err_t otherwise
 */
err_t
mld6_leavegroup(const ip6_addr_t* srcaddr, const ip6_addr_t* groupaddr)
{
	err_t         err = ERR_VAL; /* no matching interface */
	struct netif* netif;

	/* loop through netif's */
	netif = netif_list;

	while(netif != NULL) {
		/* Should we leave this interface ? */
		if(ip6_addr_isany(srcaddr) ||
		        netif_get_ip6_addr_match(netif, srcaddr) >= 0) {
			err_t res = mld6_leavegroup_netif(netif, groupaddr);

			if(err != ERR_OK) {
				/* Store this result if we have not yet gotten a success */
				err = res;
			}
		}

		/* proceed to next network interface */
		netif = netif->next;
	}

	return err;
}

/**
 * @ingroup mld6
 * Leave a group on a network interface.
 *
 * @param netif the network interface which should leave the group.
 * @param groupaddr the ipv6 address of the group to leave
 * @return ERR_OK if group was left on the netif, an err_t otherwise
 */
err_t
mld6_leavegroup_netif(struct netif* netif, const ip6_addr_t* groupaddr)
{
	struct mld_group* group;

	/* find group */
	group = mld6_lookfor_group(netif, groupaddr);

	if(group != NULL) {
		/* Leave if there is no other use of the group */
		if(group->use <= 1) {
			/* Remove the group from the list */
			mld6_remove_group(netif, group);

			/* If we are the last reporter for this group */
			if(group->last_reporter_flag) {
				MLD6_STATS_INC(mld6.tx_leave);
				mld6_send(netif, group, ICMP6_TYPE_MLD);
			}

			/* Disable the group at the MAC level */
			if(netif->mld_mac_filter != NULL) {
				netif->mld_mac_filter(netif, groupaddr, NETIF_DEL_MAC_FILTER);
			}

			/* free group struct */
			memp_free(MEMP_MLD6_GROUP, group);
		} else {
			/* Decrement group use */
			group->use--;
		}

		/* Left group */
		return ERR_OK;
	}

	/* Group not found */
	return ERR_VAL;
}


/**
 * Periodic timer for mld processing. Must be called every
 * MLD6_TMR_INTERVAL milliseconds (100).
 *
 * When a delaying member expires, a membership report is sent.
 */
void
mld6_tmr(void)
{
	struct netif* netif = netif_list;

	while(netif != NULL) {
		struct mld_group* group = netif_mld6_data(netif);

		while(group != NULL) {
			if(group->timer > 0) {
				group->timer--;

				if(group->timer == 0) {
					/* If the state is MLD6_GROUP_DELAYING_MEMBER then we send a report for this group */
					if(group->group_state == MLD6_GROUP_DELAYING_MEMBER) {
						MLD6_STATS_INC(mld6.tx_report);
						mld6_send(netif, group, ICMP6_TYPE_MLR);
						group->group_state = MLD6_GROUP_IDLE_MEMBER;
					}
				}
			}

			group = group->next;
		}

		netif = netif->next;
	}
}

/**
 * Schedule a delayed membership report for a group
 *
 * @param group the mld_group for which "delaying" membership report
 *              should be sent
 * @param maxresp the max resp delay provided in the query
 */
static void
mld6_delayed_report(struct mld_group* group, u16_t maxresp)
{
	/* Convert maxresp from milliseconds to tmr ticks */
	maxresp = maxresp / MLD6_TMR_INTERVAL;

	if(maxresp == 0) {
		maxresp = 1;
	}

#ifdef LWIP_RAND
	/* Randomize maxresp. (if LWIP_RAND is supported) */
	maxresp = LWIP_RAND() % maxresp;

	if(maxresp == 0) {
		maxresp = 1;
	}

#endif /* LWIP_RAND */

	/* Apply timer value if no report has been scheduled already. */
	if((group->group_state == MLD6_GROUP_IDLE_MEMBER) ||
	        ((group->group_state == MLD6_GROUP_DELAYING_MEMBER) &&
	         ((group->timer == 0) || (maxresp < group->timer)))) {
		group->timer = maxresp;
		group->group_state = MLD6_GROUP_DELAYING_MEMBER;
	}
}

/**
 * Send a MLD message (report or done).
 *
 * An IPv6 hop-by-hop options header with a router alert option
 * is prepended.
 *
 * @param group the group to report or quit
 * @param type ICMP6_TYPE_MLR (report) or ICMP6_TYPE_MLD (done)
 */
static void
mld6_send(struct netif* netif, struct mld_group* group, u8_t type)
{
	struct mld_header* mld_hdr;
	struct pbuf* p;
	const ip6_addr_t* src_addr;

	/* Allocate a packet. Size is MLD header + IPv6 Hop-by-hop options header. */
	p = pbuf_alloc(PBUF_IP, sizeof(struct mld_header) + sizeof(struct ip6_hbh_hdr), PBUF_RAM);

	if(p == NULL) {
		MLD6_STATS_INC(mld6.memerr);
		return;
	}

	/* Move to make room for Hop-by-hop options header. */
	if(pbuf_header(p, -IP6_HBH_HLEN)) {
		pbuf_free(p);
		MLD6_STATS_INC(mld6.lenerr);
		return;
	}

	/* Select our source address. */
	if(!ip6_addr_isvalid(netif_ip6_addr_state(netif, 0))) {
		/* This is a special case, when we are performing duplicate address detection.
		 * We must join the multicast group, but we don't have a valid address yet. */
		src_addr = IP6_ADDR_ANY6;
	} else {
		/* Use link-local address as source address. */
		src_addr = netif_ip6_addr(netif, 0);
	}

	/* MLD message header pointer. */
	mld_hdr = (struct mld_header*)p->payload;

	/* Set fields. */
	mld_hdr->type = type;
	mld_hdr->code = 0;
	mld_hdr->chksum = 0;
	mld_hdr->max_resp_delay = 0;
	mld_hdr->reserved = 0;
	ip6_addr_set(&(mld_hdr->multicast_address), &(group->group_address));

#if CHECKSUM_GEN_ICMP6
	IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_ICMP6) {
		mld_hdr->chksum = ip6_chksum_pseudo(p, IP6_NEXTH_ICMP6, p->len,
		                                    src_addr, &(group->group_address));
	}
#endif /* CHECKSUM_GEN_ICMP6 */

	/* Add hop-by-hop headers options: router alert with MLD value. */
	ip6_options_add_hbh_ra(p, IP6_NEXTH_ICMP6, IP6_ROUTER_ALERT_VALUE_MLD);

	if(type == ICMP6_TYPE_MLR) {
		/* Remember we were the last to report */
		group->last_reporter_flag = 1;
	}

	/* Send the packet out. */
	MLD6_STATS_INC(mld6.xmit);
	ip6_output_if(p, (ip6_addr_isany(src_addr)) ? NULL : src_addr, &(group->group_address),
	              MLD6_HL, 0, IP6_NEXTH_HOPBYHOP, netif);
	pbuf_free(p);
}

#endif /* LWIP_IPV6 */
